Proceedings Volume 7849

Optical Design and Testing IV

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Proceedings Volume 7849

Optical Design and Testing IV

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Volume Details

Date Published: 5 November 2010
Contents: 12 Sessions, 89 Papers, 0 Presentations
Conference: Photonics Asia 2010 2010
Volume Number: 7849

Table of Contents

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Table of Contents

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  • Front Matter: Volume 7849
  • Novel Optical System Design I
  • Fabrication and Testing
  • Aberration Theory and Image Analysis
  • Optical Measurement
  • Nonimaging Optics and Illumination Optics
  • Display System Design
  • Novel Optical System Design II
  • LED Illumination Systems
  • Metamaterial Design and Novel Photonics Devices
  • Interferometry in Optical Testing
  • Poster Session
Front Matter: Volume 7849
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Front Matter: Volume 7849
This PDF file contains the front matter associated with SPIE Proceedings Volume 7849, including the Title Page, Copyright Information, Table of Contents, and the Conference Committee listing.
Novel Optical System Design I
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Developments in optical coherence microscopy
J. P. Rolland, P. Meemon, K. P. Thompson, et al.
Optical Coherence Microscopy (OCM) utilizes a high NA microscope objective in the sample arm to achieve an axially and laterally high resolution OCT image. An increase in NA, however, leads to a dramatically decreased depth of focus (DOF), and hence shortens the imaging depth range so that high lateral resolution is maintained only within a small depth region around the focal plane. One solution to increase the depth of imaging while keeping a high lateral resolution is dynamic-focusing. Utilizing the voltage controlled refocus capability of a liquid lens, we have recently presented a solution for invariant high resolution imaging using the liquid lens embedded within a fixed optics hand-held custom microscope designed specifically for optical imaging systems using a broadband light source centered at 800 nm with a 120 nm bandwidth. Subsequently, we have developed a Gabor-Domain Optical Coherence Microscopy (GD-OCM) that utilizes the high speed imaging of spectral domain OCT, the high lateral resolution of OCM, and the ability of real time refocusing of our custom design variable focus objective. Finally, key developments in Phase-Resolved Doppler OCT (PR-DOCT) are key enablers to combine high-resolution structural imaging with functional imaging. In this paper we review achievements in GD-OCM and detail how portions of in-focus cross-sectional images can be extracted and fused to form an invariant lateral resolution image with multiple cross-sectional images acquired corresponding to a discrete refocusing step along depth enabled by the varifocal device. We demonstrate sub-cellular resolution imaging of an African frog tadpole (Xenopus Laevis) taken from a 500 μm × 500 μm cross-section as well as cellular imaging in in vivo skin. Finally, A novel dual-detection full-range Fourier-domain optical coherence tomography system was developed that provides 7 μm axial resolution (in air) at about 90 kHz axial scan rate for mirror-image phase resolved Doppler imaging in an African frog tadpole and an in vivo human finger.
Optical design rules of a camera module with a liquid lens and principle of command for AF and OIS functions
Eric Simon, Bruno Berge, Franck Fillit, et al.
We have developed a miniature liquid lens component based on electro-wetting. It is designed to be plugged on a fix focus camera module lens to provide both optical image stabilization (OIS) and auto-focus (AF) functions without any mobile mechanical parts. The OIS/AF liquid lens component features a conical shape supporting the liquid interface in order to maintain a stable optical axis and a multi-electrode design able to induce an average tilt of the liquid interface when a bias voltage is applied to the different electrodes. The miniature size of the OIS/AF liquid lens component is well adapted to imaging applications with ¼ inch, 1/3 inch and possibly 1/2.5 inch sensor formats. We will present general rules for the optical design with an OIS/AF liquid lens. In this context, we will describe a simple calculation, based on the well known Maréchal criterion, to estimate the optical wave front error requirement of an optical component positioned in the aperture stop plane of an imaging lens design to perform images with a pixel resolution quality. We will also present the principle of command of a multi-electrode liquid lens in order to perform AF and OIS functions with an optimal image quality.
The design of nonsymmetrical optical system in the detection of laser echo
Hongbo Xie, Lin Han, Fulin Li, et al.
A solution of the nonsymmetrical optical system to collect laser echo light is presented, which is based half on imaging optics and half on non-imaging optics. The difficulty in the design of the large field and large aperture optical system used to collect the laser echo is analyzed, and the influence of the aberration and cylindrical lens to the system is illuminated. The whole system is initially designed by CODE V, and the transmittance of system is analyzed by LightTools. The result shows that the transmittance of any interested direction is more than 80%, and the system is feasible in practice.
Modeling anamorphic optical surfaces in the MOEMS-based zoom lens
MOEMS (Micro-opto-electromechanical systems) based zoom lens is a kind of optical system combining the off-axis reflective DM (deformable mirrors) and the on-axis refractive elements. It usually has two deformable mirrors. The magnification of one DM would be variable while its surface profile is changed by controlling the actuators, which results in a focal shift in the image space of the zoom lens. To compensate the variation of the focal plane position, the surface profile of another DM is varied. Therefore the focal length of the whole optical system would be varied and have a stabilized image position. In this paper, modeling anamorphic optical surfaces in the MOEMS-based zoom lens is described. The anamorphic profile of the DM is designed to satisfy the following requirements. First, the aberration coefficients of the DMs and the refractive surfaces are composed in the vector space to achieve the coefficients of the system. And the initial configuration of the refractive elements is determined to fulfill the system requirements and specifications at the wide angle and long focal length positions. Then the anamorphic profile of the DM is designed to compensate the off axis aberrations by creating two zeros of low order astigmatism, achieved a reasonable result.
Fabrication and Testing
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An analytic expression for the field dependence of FRINGE Zernike polynomial coefficients in optical systems that are rotationally nonsymmetric
Kevin P. Thompson, Kyle Fuerschbach, Jannick P. Rolland
Zernike polynomials have emerged as the preferred method of characterizing as-fabricated optical surfaces. From here, over time, they have come to be used as a sparsely sampled representation of the state of alignment of assembled optical systems both during and at the conclusion of the alignment process. We previously developed the field dependence that analytically interconnects the coefficients of the Zernike polynomial (which has to-date been characterized only by its aperture dependence) as a more complete representation of an aligned, rotationally symmetric optical system. Here, we extend this analytic expression for the RMS wavefront error to encompass the prediction of the performance of a misaligned optical system by expressing the field dependence within the framework of nodal aberration theory. This significant expansion to this valuable polynomial provides an important new tool for characterizing high performance optical systems throughout the optical design, fabrication, assembly, and interim and acceptance test process.
Corrective, deterministic, and/or generative sub-aperture finishing
Ken Tanimura, Kazuto Hori, Noboru Sugimoto, et al.
Sub-aperture finishing is applied for the correction of the optical surface. Most important issue is how to keep stabilized sub-aperture tool contact (footprint) condition and control a removal rate and a dwell time. Magneto Rheological Finishing is one of the most advanced sub-aperture finishing process. For several years, this process was applied for a correction of spherical or flat surface after precisely measured surface data. The authors have reviewed and improved this finishing process to get more reliable finishing result. This paper shows MRF is furthermore cable to "generate" a desired optical profile from existing surface under completely controlled finishing circumstance and metrology feedback.
Design of optical stress sensor using single electro-optic and photo-elastic crystal
Based on mutual compensation characteristic of the photoelastic and electrooptic birefringence or phase retardation in crystal or glass, an optical stress sensor is designed in principle by use of single bulk crystal or glass. Particularly, the crystal is used as both stress sensing element and electrooptic phase modulator. The configuration of conventional optical stress sensor is simplified, and closed-loop stress measurement is also possible.
Separating misalignment from misfigure in stigmatic null tests of conic mirrors
Qinfang Chen, Zhen Ma, Yingcai Li, et al.
Null testing of off-axis conic surface at the pair of conjugate foci can add sensitivity resulting from double pass off the test piece. However, the alignment procedure of the test is difficult. The main reason is that the return wavefront from off-axis aspheric surface is not rotationally symmetric so that the observer cannot tell if the wavefront asymmetries are due to surface or misalignment errors. In this paper, we analyze the effect of misalignments on test results with the optical path method, and derive an equation for misalignment-induced aberrations. Next we present an optimum method for the removal of alignment errors. As an example the method is applied to the alignment of an off-axis mirror. After several alignments, a misaligned test system giving 0.093λ rms wavefront error can be adjusted to 0.024λ, at 0.6328 microns.
MTF measurement and imaging quality evaluation of digital camera with slanted-edge method
Modulation Transfer Function (MTF) is the spatial frequency response of imaging systems and now develops as an objective merit performance for evaluating both quality of lens and camera. Slanted-edge method and its principle for measuring MTF of digital camera are introduced in this paper. The setup and software for testing digital camera is respectively established and developed. Measurement results with different tilt angle of the knife edge are compared to discuss the influence of the tilt angle. Also carefully denoise of the knife edge image is performed to decrease the noise sensitivity of knife edge measurement. Comparisons have been made between the testing results gained by slanted-edge method and grating target technique, and their deviation is analyzed.
The ground calibration of far ultraviolet scanning imaging spectrometer (FUSIS)
The far ultraviolet scanning imaging spectrometer (FUSIS) is used to measure the composition and distribution of the main molecules and atoms in the Earth's upper atmosphere. It is an important instrument in investigation of the physical and chemical processes in the Earth's upper atmosphere. FUSIS works between 120nm to 180nm, its spectral resolution is better than 1.0nm and its spatial resolution is 8 pixels. This paper describes a kind of ground calibration method and facility of FUSIS. The FUV light is invisible, so all works must be done in high vacuum. The calibration facility includes the FUV light source, collimator, and the vacuum chamber. The pumps of vacuum system can debase the pressure down to 5×10-5Pa. Calibration experiments are accomplished in the vacuum chamber. The spectral calibration of FUSIS is achieved with the linear interpolation method. The radiation transfer function is deduced. But some factors in the function such as reflection components' reflectivity and detector's quantum efficiency are hard to test accurately. So we use a radiation correction matrix instead of the transfer function in practice. Assuming the FUSIS instrument is a blackbox, the matrix can be tested by experiments. FUSIS can get the absolute radiation intensity of target by calling the matrix.
Aberration Theory and Image Analysis
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In the era of global optimization, the understanding of aberrations remains the key to designing superior optical systems
Historically, a thorough grounding in aberration theory was the only path to successful lens design, both for developing starting layouts and for design improvement. Modern global optimizers, however, allow the lens designer to easily generate multiple solutions to a single design problem without understanding the crucial importance of aberrations and how they determine the full design potential. Compared to pure numerical optimization, aberration theory applied during the lens design process gives the designer a much firmer grasp of the overall design limitations and possibilities. Among other benefits, aberrations provide excellent insight into tolerance sensitivity and manufacturability of the underlying design form. We explore multiple examples of how applying aberration theory to lens design can improve the entire lens design process. Example systems include simple UV, visible, and IR refractive lenses; much more complicated refractive systems requiring field curvature balance; and broadband zoom lenses.
Why are there so many system shapes in lens design?
The presence of many local minima in the merit function landscape is perhaps the most difficult challenge in lens design. We present a simplified mathematical model that illustrates why the number of local minima increases rapidly with each additional lens added to the imaging system. Comparisons with results obtained with lens design software are made for the design landscape of triplets with variable curvatures, a problem that is nontrivial, but still simple enough to be analyzed in detail. The mathematical model predicts how many types of local minima can exist in the landscape of the global optimization problem and what are, roughly, their curvatures. This model is mathematically quite general and might perhaps be useful as an analogy for understanding other global optimization problems as well, there where the number of local minima increases rapidly when more components of the same kind are added in the model of the problem.
A simulation imaging method for actual optical system and results analysis
Fen Neng, Qiangsheng Liu, Hongbo Shang, et al.
The image quality is the most direct method for evaluating actual optical system's quality. Imaging of standard feather image, such as resolution plate, comet and so on is also frequently used in lens test in optical industry. The existing simulation method for optical system can be divided into two categories. One is using ideal optical system model to simulate image the object formed, but the actual parameters, aberration, processing and assembly of the optical system cannot be considered. The other can calculate the special field's Spot Diagram, Point Spread Function and Module Transfer Function by the optical design software. It is widely used for optimization (design) and image restoration. In this paper, the actual optical system is simulated by our self-developed simulation software, the target image is entered, the ray tracing method is used and the simulated image is received, which is formed by the object image of the practical optical system with errors. Known parameters of the optical system are used in this article. The correctness of simulation results is demonstrated. And the targeted photorealistic images with colors and photometric information can be gotten by the simulation software, and the more rays be used, the more fields be cut, the simulated image much closer to the actual image. The errors possible existing in optical system processing and assembly, such as eccentric, tilt or surface error are considered in our simulation software, and the simulated image we get is affected by these factors. So that we can give the reasonable tolerances, speed up the development efficiency and reduce cost.
Several factors affecting self-thermal radiation of cryogenic infrared optical system
Baolin Du, Li Lin, Meng Cai, et al.
In cryogenic infrared optical system, any inner component of this system above absolute zero will emitt infrared radiation. These radiation, striking detector surface through transmitting in optical system, makes self-stray radiation of infrared system. This self-stray radiation is dominant stray radiation in cryogenic infrared system, and it is a key factor of reducing image quality of cryogenic infrared system. How to suppress self-stray radiation becomes a critical work in the whole design process of cryogenic infrared system. Take a space remote sensor as an example, distribution change of self-thermal radiation on the detector surface when the space remote sensor under different temperature, emissivity or surface state is presented in this paper. Phenomena of self-thermal radiation in optical system is also researched from two aspects of self-radiation of emitting sources and transmission of thermal radiation in optical system. Consequently, several key factors of making thermal radiation of detector surface change are found. Therefore, corresponding measures of suppressing thermal radiation are proposed. And self-stray radiation of cryogenic infrared optical system has been effectively suppressed and the performance of the space remote sensor has been ensured within its technical requirement.
Analysis methods for polarization state and energy transmission of rays propagating in optical systems
Chao Liu, Qiangsheng Liu, Zhaofeng Cen, et al.
Polarization state of only completely polarized light can be analyzed by some software, ZEMAX for example. Based on principles of geometrical optics, novel descriptions of the light with different polarization state are provided in this paper. Differential calculus is well used for saving the polarization state and amplitudes of sampling rays when ray tracing. The polarization state changes are analyzed in terms of several typical circumstances, such as Brewster incidence, total reflection. Natural light and partially polarized light are discussed as an important aspect. Further more, a computing method including composition and decomposition of sampling rays at each surface is also set up to analyze the energy transmission of the rays for optical systems. Adopting these analysis methods mentioned, not only the polarization state changes of the incident rays can be obtained, but also the energy distributions can be calculated. Since the energy distributions are obtained, the surface with the most energy loss will be found in the optical system. The energy value and polarization state of light reaching the image surface will also be available. These analysis methods are very helpful for designing or analyzing optical systems, such as analyzing the energy of stray light in high power optical systems, researching the influences of optical surfaces to rays' polarization state in polarization imaging systems and so on.
Optical Measurement
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Adaptive intensity stabilization of ultra-short optical pulse for optical measurement and metrology
Tsuyoshi Konishi, Kentaro Kawanishi
Nonlinear optical effects such as multi-photon absorption, Raman effect etc. have been attracted a considerable attention and used in various fields such as light source development, optical measurement, optical metrology, optical communication, optical fabrication and so on. Since, however, nonlinear optical effects are very sensitive to intensity fluctuation of input pulses, intensity stabilization of a light source is a very important issue for their applications. In this talk, the current progress on an all-optical limiter for intensity stabilization is reviewed and some achievements by using a SPM-based optical limiter are demonstrated.
Extraction and analysis of the image in the sight field of comparison goniometer to measure IR mirrors assembly
The comparison goniometer is widely used to measure and inspect small angle, angle difference, and parallelism of two surfaces. However, the common manner to read a comparison goniometer is to inspect the ocular of the goniometer by one eye of the operator. To read an old goniometer that just equips with one adjustable ocular is a difficult work. In the fabrication of an IR reflecting mirrors assembly, a common comparison goniometer is used to measure the angle errors between two neighbor assembled mirrors. In this paper, a quick reading technique image-based for the comparison goniometer used to inspect the parallelism of mirrors in a mirrors assembly is proposed. One digital camera, one comparison goniometer and one set of computer are used to construct a reading system, the image of the sight field in the comparison goniometer will be extracted and recognized to get the angle positions of the reflection surfaces to be measured. In order to obtain the interval distance between the scale lines, a particular technique, left peak first method, based on the local peak values of intensity in the true color image is proposed. A program written in VC++6.0 has been developed to perform the color digital image processing.
Nonimaging Optics and Illumination Optics
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Free-form Köhler nonimaging optics for photovoltaic concentration
Concentration Photovoltaics (CPV) is one of the most promising areas for competitive solar electricity production. This promise relies upon the use of high-efficiency triple-junction solar cells (which already have proven efficiencies over 41%) and upon advanced optics designs, which allow for high concentration concurrent with high manufacturing tolerances, both key elements for low cost mass production. In this paper we will present the progress in the development of the most advanced CPV optical designs at present. These are based on free-form optics using Köhler homogenization. The degree of freedom of using free-forms allows the introduction of multiple functionalities in a few optical elements, which provide the required concentration with high tolerance and excellent light homogenization. Different families are presented. The first group uses a Fresnel lens as a primary optic (called the FK concentrator and the F-RXI concentrator) and a second group using mirrors as primaries (the XR and the XXR). How they compare among them and also with classical designs will be discussed. The FK is in the process of being brought to market and has already experimentally proven module electrical (DC) efficiencies over 30% (equivalent to over 32% with correction to Tcell=25ºC) with no AR coatings at a concentration of 625x with high tolerance angle (over ±1.2º).
Different illumination modes in microlithography illumination system
Xing Han, Lin Li, Yifan Huang, et al.
Illumination system is one of the most important parts of the micro-lithography object lens. Its performance can greatly affect the lithography machine's etching graphic quality. In this paper, we discuss a DUV micro-lithography illumination system which can achieve high uniformity and a large illuminated area on the mask. According to the large numerical aperture requirement, a refractive illumination system is designed and optimized with software ZEMAX. The system also meets the requirement of large illumination area on the mask, and no aspherical lens is used. Characters of different illumination structures and modes are introduced here. Then by using the software of TracePro, illumination systems with different kinds of aperture are modeling and illuminaces are analyzed. We research effect of illuminace on the mask which bring by different kinds of aperture. Also in this paper, we make a study of relationship between different illumination mode and different kinds of graphics. Finally, we compare the results and give suggestion about how to choose illumination mode. That is meaningful for choosing different aperture in illumination system of microlithography.
Display System Design
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Depth-fused multi-focal plane displays enable accurate depth perception
Many different approaches to three-dimensional (3-D) displays have been explored, most of which are considered to be stereoscopic-type. The stereoscopic-type displays create depth perception by presenting two perspective images, one for each eye, of a 3D scene from two slightly different viewing positions. They have been the dominant technology adopted for many applications, spanning the fields of flight simulation, scientific visualization, medicine, engineering design, education and training, and entertainment systems. Existing stereoscopic displays, however, lack the ability to produce accurate focus cues, which have been suggested to contribute to various visual artifacts such as visual fatigue. This paper will review some recent work on vari- and multi-focal plane display technologies that are capable of rendering nearly correct focus cues for 3D objects and these technologies have great promise of enabling more accurate depth perception for 3D tasks.
Free form optical system design with differential equations
The general Wassermann-Wolf differential equations were derived to design an off-axis free form surface (FFS) prism head mounted display (HMD) system. A FFS prism HMD system with 20° degree, 8mm exit pupil and 15mm-effective focal length was designed and the image qualities were analyzed.
The design of light pipe with microstructures for touch screen
Bo Yang, Kan Lu, Pengfei Liu, et al.
Touch screen has a very wide range of applications. Most of them are used in public information inquiries, for instance, service inquiries in telecommunication bureau, tax bureau, bank system, electric department, etc...Touch screen can also be used for entertainment and virtual reality applications too. Traditionally, touch screen was composed of pairs of infrared LED and correspondent receivers which were all installed in the screen frame. Arrays of LED were set in the adjacent sides of the frame of an infrared touch screen while arrays of the infrared receivers were fixed in each opposite side, so that the infrared detecting network was formed. While the infrared touch screen has some technical limitations nowadays such as the low resolution, limitations of touching methods and fault response due to environmental disturbances. The plastic material has a relatively high absorption rate for infrared light, which greatly limits the size of the touch screen. Our design uses laser diode as source and change the traditional inner structure of touch screen by using a light pipe with microstructures. The geometric parameters of the light pipe and the microstructures were obtained through equation solving. Simulation results prove that the design method for touch screen proposed in this paper could achieve high resolution and large size of touch screen.
Carrier feed-through analysis of heterodyne lidar system
Jiqiang Wang, Zhiqiang Song, Chang Wang, et al.
A novel heterodyne continuous wave lidar system based on single-mode fiber (SMF) components and instruments is reported. In order to improve the signal-to-noise ratio (SNR) of heterodyne lidar system, the four causes producing carrier feed-through are presented, including: (1) the return loss of optical antenna; (2) the direction of fiber circulator; (3) the extinction ratio of acousto-optic frequency shifter (AOFS); (4) close object's reflection. Then theoretical analysis and experimental study for the methods of eliminating carrier feed-through are conducted. The results demonstrate that carrier feed-through mainly arises from the non-ideality of optical components. By improving the traditional heterodyne optical structure and enhancing the performance of optical components, the carrier feed-through power can be decreased by more than 20dB.
Novel Optical System Design II
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Optical design of non-CaF2 of middle and low power flat-field apochromatic metallographic micro-objective
Ze-xin Xiao, Jie Cao, Ran Xiao, et al.
Based on the optical apochromatic system theory and referencing photographic objective to make similar innovation, the middle and low power apochromatic metallographic microobjective is constructed. In the design of low power objective, triplet photographic objective(+, -, +) is transplanted and applied to 5×objective. Referencing parameters of Orthometar processor objective and complication of triplet graphic objective are applied to middle power objective. The 8× and 10× objectives with flat-field and apochromatic can be designed successfully using iterative optimization in OSLO.
Conceptual design of airborne daytime infrared star cameras
Yuying Zhou, Weimin Shen, Feng Wu, et al.
Star camera is a kind of sensitive attitude sensors used for navigation of space vehicles. In order to use it on aircrafts in daytime, the conceptual design and the principle of airborne daytime infrared star cameras are introduced in this paper, as there is enough number of stars in near infrared band to be used as reference of a star camera for calculating attitude. Through analyzing the atmospheric scattering background light intensity for different altitudes, observing angles, and solar angles with Modtran software, and considering IR FPA (infrared focal plane array) performance, shot noise and the required star magnitude for daytime star trackers and sensors, the optical system parameters, i.e. FOV (field of view), clear aperture diameter and effective focal length, are determined according to the required SNR (signal to noise ratio).
Design of a multi-channel quasi-optical front-end at terahertz bands
Zheng Lou, Sheng-Cai Shi
This paper presents a proposal for a quasi-optical design for a terahertz band multi-channel front-end that has the potential application in China's future 5m terahertz telescope in Dome A, Antarctica. The front-end provides quasioptical beam coupling between the Cassegrain antenna system and the heterodyne receiver arrays operating in two bands simultaneously. Numerical verification of the design was performed using the Gaussian optics and parallelized physical optics algorithms.
LED Illumination Systems
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LED lighting module design based on a prescribed candle-power distribution for uniform illumination
Jin-Jia Chen, Kuang-Lung Huang, Te-Yuan Wang, et al.
A simple approach is presented to design an LED lighting module to provide a uniform illumination. The reflector of the module is designed using a prescribed candle-power distribution to achieve a uniform illumination on a target surface. Both the design methodology and the construction of the reflector are stated in detail. The optical efficiency and uniformity of the module are calculated according to a ray-tracing result. In addition, the effects of the reflector's aperture and the LED chip size on the optical efficiency and uniformity are also investigated that the result can provide a reference to LED-luminaire designers and manufacturers.
Lens design of street lamp for integrated high-power LED
Hong Liu, Lanfang Jiang, Lida Hu
The paper studies the photometric patch design way of aspherical lens to solve the difficulty of photometric design for integrated high power LED street lamp, which has the demand of prescribed rectangular illumination. It divides lens surface into several corresponding patches according to the subarea of road surface, and controls luminous beam to appointed area in order to adjusting radiation shape through controlling parameters of lens surface. Based on the optics simulation software LightTools the paper takes maximum luminance, average luminance and length of rectangular illumination as optimal objects, and optimizes the parameters of photometric patch design optimal model for aspherical lens of integrated high power LED street lamp using orthogonal experimental method. And the optimal result is good and satisfies the relational national standards about street and road luminance. The paper validates rationality of photometric patch design method and validity of the lens through experiment. The study puts forward an effective design way for strict photometric demand about LED street lamp.
Multi-segment freeform LED uniform lens with low reflective loss
Liangping Xia, Shaoyun Yin, Xiaochun Dong, et al.
The secondary optical lens of the light-emitting diode (LED) constructed with freeform surface plays more and more important role in common illumination. The reflective loss at the freeform interfaces is discussed in this work. To restrict the reflective loss of the rays with the large incident angle, the freeform surface design rule is proposed. In this rule, the maximum deflexion angle of the refractive surface is 25° for a single freeform interface when choose PMMA to be the lens material, and the total reflection surface is introduced to control the rays which cannot be dealt by the refractive surfaces. The lens examples based on this rule are constructed by multi-segment freeform surfaces and the results show that the reflective loss is controlled less than 10%.
Metamaterial Design and Novel Photonics Devices
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Frequency tunable electromagnetic metamaterial based on mechanical movement method
Yifu Wang, Xiaochun Dong, Guishan Yuan, et al.
A frequency tunable electromagnetic metamaterial is proposed based on mechanical movement method. Two rings are etched against each other on two separate substrates and the two substrates can be adjusted to move relatively. Thus, the resonant frequency can be modulated due to the changed coupling capacitance between the rings according to equivalent circuit theory. Simulation results show that the transmissions (S21) can be continuously adjusted, and the retrieved effective parameters based on simulated scattering parameters reveal that the negative permittivity is available and the negative permittivity frequency region can be tuned downward or upward by slipping the rings either along or perpendicular to the gap's directions. By combining frequency modulations in the two directions, resonant frequency can be shifted from 6.2 GHz to 8.7 GHz, which has realized an efficient modulation in a broad frequency range. The proposed tunable metamaterial has potential applications to design dual band, multi-band antennas and frequency reconfigurable antennas.
Plasmonic analogue of atom systems with two-level to four-level configurations in metamaterials
Hua Xu, Byoung S. Ham
Electromagnetically induced transparency (EIT) whose mechanism is in destructive quantum interference has been studied in a plasmonic system of metamaterials. Here we study the relation between the plasmonic EIT and atom EIT in multilevel configurations. For numerical simulations finite-difference time-domain (FDTD) method and density-matrix approach have been used. In the analysis, asymmetric EIT in the plasmonic system is studied for the fundamental understanding of geometry-based transparency. The plasmonic EIT has potential for plasmonic switching using on-demand transparency control.
Fluorescence enhancement of the organic light-emitting material based on self-assembly technology
Maoguo Zhang, Jinglei Du, Yidong Hou, et al.
In this paper, a simple Tris (8-hydroxyquinolinato) aluminium (Alq3) /Ag particles/glass substrate trilayer structure was fabricated to investigate the metal-enhanced photoluminescence phenomena. The polystyrene sphere (PS) self-assembly technology was used to constitute nanoscale metallic particle array on the glass substrate. Based on the localized surface plasmons (LSPs) excited by these metallic particles, fluorescence enhancement of the organic light-emitting material has been actualized. The finite-difference time-domain (FDTD) simulations have been performed to analyze the experiment results. Subsequently, an optimized design which depended on the extinction cross-section of the metallic particles was proposed to improve the enhancement factor.
Performance analysis of wavelength conversion in SOI waveguides
Ashiq Hussain, Xinzhu Sang, Chongxiu Yu, et al.
In this paper the parametric amplification and wavelength conversion in a 1cm long silicon-on-insulator (SOI) waveguide has been investigated numerically using coupled wave equations. The wavelength conversion efficiency is analyzed and performance is presented with effect of pump/signal power and wavelength. The influence factors of noise figure are also considered.
The high-numerical aperture photonic crystal fibers and application in astronomy
Weimin Sun, Xiaoqi Liu, Haijiao Yu, et al.
In order to detect the weak light of the protostars in astronomy, we design a new type of photonic crystal fibers with high numerical aperture. Through controlling the number and the diameter of the air holes around the central fiber core, the numerical aperture can also be adjusted to apt different applications. With the help of the big air holes, the loss can be reduced to less than 0.1dB/km. So this kind of high numerical aperture fibers has the strong ability to collect light and the loss is very low.
Interferometry in Optical Testing
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A best-fit sphere definition capable of reducing dynamic range in aspheric surface testing
Feng Xie, Qun Hao, Qiudong Zhu, et al.
In order to fit the requirements of aspheric surface testing, a new best-fit sphere definition is proposed. The application and importance of the best-fit sphere definition in aspheric surface testing are analyzed. According to mass simulations, the characteristics of the best-fit sphere are analyzed, and the formulas of its sphere center and radius are given. The analysis indicates that the best-fit sphere definition is directly relative to the manufacture difficulty of CGH and the testing difficulty of aspheric surface to represent the testing difficulty of aspheric surface and reduce the testing dynamic range, and is beneficial to reduce the testing error of laser deflectometry and expand testing range.
White light interferometry for fast areal surface measurement based on GPGPU
Jing Wang, Kaiwei Wang, Shuangshuang Zhao, et al.
White-light interferometry is always an extremely useful and powerful tool for optical surface measurement. In this paper, a novelty method based on rapid positioning and fast surface measurement is proposed. The adjustment of optical path difference (OPD) is done automatically by a wavelength scanning method, and the processing of white-light interference patterns is accelerated by GPGPU which stands for General-Purpose computation on Graphics Processing Units, also known as GPU Computing. Graphics Processing Units are high-performance many-core processors in which the data are processed in parallel. As a result, the time we need to obtain a surface shape is reduced to ten percents compared with the conventional white-light interferometry. With these advantages, it is possible to measure a rough and areal surface in a short time.
Single-shot white-light dispersive interferometric profilometer
Pei Zhu, Kaiwei Wang, Shuangshuang Zhao
Traditional interferometric profilemeter suffers from phase ambiguity problem and sensitivity to environmental disturbance, thus preventing their applications for on-line surface inspections. We propose a new method to obtain the object surface's two-dimensional profile in a single shot using a dispersive interferometer. An air-spaced Fabry-Perot etalon was applied in order to decompose the light from the broadband source into discrete monochromatic constituents with equal wavelength interval. A blazed grating is implemented to effectively separate the interferograms of difference wavelength. As a result, the interference patterns of different wavelengths distributed separately on the CCD camera. By analyzing these patterns one can get the configuration of the original surface. A one-dimensional profiling experiment is carried out to test a surface with steps and the mean error of the result is below 0.2μm.
Poster Session
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Comprehensive performance analysis of popular odd-symmetric phase masks used for wave-front coded imaging system
Hui Zhao, Yingcai Li
Wave-front coding was proposed in 1995 and is a powerful system-level technique used to extend the depth of field (DOF) of incoherent imaging system. The key to wave-front coding lies in the design of suitable phase masks which make the imaging system insensitive to defocus and defocus-related aberrations. Among all phase masks used for wave-front coding, odd-symmetric types are dominant and can provide larger extended DOF. With the acceptable degradation of MTF (Modulation Transfer Function) taken as a criterion, optimization procedure is used to obtain the optimum parameters for popular odd-symmetric phase masks and then a comprehensive analysis is carried out by considering four factors: DOF extension capability, sensitiveness to elementary aberrations, PSF (Point Spread Function) shifting effect and restorability of intermediate blurred images. To the best of our knowledge, the comprehensive analysis on performance of popular odd-symmetric phase masks, as done in this manuscript, has not been made before. So, the work reported here could be considered as a complementary part to the field of wave-front coding.
Defocus measuring the focal length of microlens array by grating prismatic interference
Xianchang Zhu, Xuedong Cao, Shibin Wu, et al.
Microlens-arrays have been used in many fields; it's difficult to measure the focal length by traditional method. This paper introduces a new technique for the focal length measurement. Place the grating close-by the focal point and make the +1 order and 0 order rays diffracted from the grating interfering, from the number of interference stripe we can get the grating defocus, ulterior finish the focal length testing. In this paper, we enumerate the expression between the defocusing and the interference stripe number. At the same time, we make an experiment to prove the feasibility. The experiment result shows that this technique has a higher testing accuracy and efficiency as opposed to traditional method.
Index profile of gradient refractive index ball lens using the nondestructive measurement method
Zhao Cai, Hao Lv, Aimei Liu, et al.
In this paper, the polynomial which is used to calculate the gradient refractive index profiles of gradient refractive index ball lenses is given, and the gradient refractive index profiles of gradient refractive index ball lenses can be measured using shearing interferometer rapidly, automatically and nondestructively. Comparing the measuring results with the previous reports, we find the gradient refractive index profiles of gradient refractive index ball lenses are precisely measured using the shearing interferometer.
Nanostructures with near-zero refractive index in mid-infrared region
Hao Dong, Chuankai Qiu, Zugao Ni, et al.
The near-zero-index metamaterials (NZIMs) have been extensively studied in recent years. In this letter, we show that a NZIM can be achieved in metallic nanostructures in Mid-IR region. The structure is composed of parallel metal stripes arrays, so it can be easily fabricated. By scaling the dimensions of the structure, the effect can be tuned over a large bandwidth. Analysis is carried out to study the influence of the NZIM on infrared transmission in 28.3THz (10.6μm). The multilayer homogeneous medium model is employed based on the effective medium theory. Additionally, the theoretical analysis also provides a new method of determining the effective thickness of metamaterials, which is usually complicated. The results suggest that the ratio of the amplitude after the light beam propagates through the NZIM to that before it is about 80%, and there is a negative variation in the phase of the light transmitted through the NZIM, which is in agreement with numerical simulation. Simulation also indicates that there is a strong enhancement of the electric field between the metal stripes arrays, which plays an important role in the phase delay. This metamaterial has the potential to be used in some devices such as in waveguides.
Optimization design and error analysis of moiré deflection system
Litong Song, Shibin Wu, Long Kuang, et al.
Moiré deflectometry is used for the measurement of focal lengths of optical lenses in this paper. Detailed uncertainty analysis is done, and achievable accuracy is discussed. To increase the measurement accuracy, we propose two useful ways by changing the two systemic parameters (angle and space between two gratings). Firstly, we find that the space between two gratings affect the error from the tilt angle of moiré fringe greatly. And optimum space between two gratings for minimum error is referred to. In the other hand, enhancing the angle between the two grating's ruling's lines moderately can reduce error from the angle of two gratings greatly. Theoretical analysis and experimental results indicate that, higher measurement accuracy can be achieved by changing the systemic parameters opportunely.
Reflective foveated optical imaging system based on liquid crystal spatial light modulator
Qing-qing Peng, Jun Chang, Shu-long Feng, et al.
Based on reflective liquid crystal spatial light modulator (SLM), a new foveated optical imaging system is proposed. High quality imaging can be realized at any region of interest (ROI) within the field-of-view (FOV) by utilizing the SLM to correct the aberration of different regions dynamically. A reflective cassegrain optical structure is proposed, which is designed, optimized and matched with the reflective SLM to construct a more practical foveated imaging system. This reflective imaging system has a large aperture so that enough light can reach the image plane. It also makes the total length of the system shorter and therefore more practical. We also simulate and analyze the system. This kind of foveated optical imaging system can be applied in wide FOV imaging aspects to reduce bandwidth and optics complexity, and to achieve weight reduction and miniaturization.
Design and analysis of a sub-aperture scanning machine for the transmittance measurements of large-aperture optical system
For measuring large-aperture optical system transmittance, a novel sub-aperture scanning machine with double-rotating arms (SSMDA) was designed to obtain sub-aperture beam spot. Optical system full-aperture transmittance measurements can be achieved by applying sub-aperture beam spot scanning technology. The mathematical model of the SSMDA based on a homogeneous coordinate transformation matrix is established to develop a detailed methodology for analyzing the beam spot scanning errors. The error analysis methodology considers two fundamental sources of scanning errors, namely (1) the length systematic errors and (2) the rotational systematic errors. As the systematic errors of the parameters are given beforehand, computational results of scanning errors are between -0.007~0.028mm while scanning radius is not lager than 400.000mm. The results offer theoretical and data basis to the research on transmission characteristics of large optical system.
Compensation ability evaluation of part-compensation lens based on slope asphericity
Feng Xie, Qun Hao, Qiudong Zhu, et al.
The accurate evaluation on the compensation range of part-compensation lens is beneficial to guide the design of part-compensation lens and realize fast testing on many aspheric surfaces. The prior evaluation methods based on asphericity have error judge occurred, thus reduce the compensation range of part-compensation lens negatively, further increase the testing time of aspheric surface. Therefore, an evaluation method based on slope asphericity that fits testing requirements is proposed to evaluate the compensation range of part-compensation lens. Mass simulations are processed to compare different evaluations and the effect of aspheric surface parameters on compensation range evaluation is analyzed. Additionally, the operation mechanism of part-compensation lens is analyzed from slope match of rays. The results indicate that accurate evaluation can be realized via using slope asphericity, thus is beneficial to design a part-compensation lens with the compensation range as large as possible.
Research on special type vertical illumination system of metalloscope
Ran Xiao, Ze-xin Xiao, Jie Cao
Kohler illumination is the typical concentrated illumination system of microscope, and is widely used in all kinds of microscopes. Because the conjugate distance of large NA(numerical aperture) kohler illumination system is long, the application of it in general metalloscope is restricted. With the purpose of coordinating the contradiction between them, a kind of large NA and special type vertical kohler illumination is explored according to the optical principle of kohler illumination. Practice has proved that the system can get the same good performance with traditional kohler illumination system. However, the optical tube length and the number of lens of the system are about half of that of the typical structure, and they have higher performance-cost ratio. This paper also introduced a creation design of focal distance offset amount of the annular lens light group using OSLO optical software, and it can be used for dark light group critical lighting through the method of calculating annular lens. The light group has fairly good adaptability with optical properties of the objective, providing a maneuverability practical method of designing refractive dark field critical illumination.
Tip-tilt adaptive correction based on stochastic parallel gradient descent optimization algorithm
Huimin Ma, Pengfei Zhang, Jinghui Zhang, et al.
Adaptive optics correcting technique based on stochastic parallel gradient descent (SPGD) control algorithm is an alternative approach which is independent of wavefront sensor and optimizes the performance metric directly. In this paper we establish a simulation model of tip-tilt adaptive optics system, where SPGD optimization algorithm is used to correct the tip-tilt aberration induced by dynamic turbulence. The distance between the measured centroid of a blurring image and the demarcated centroid of the ideal image is considered as the system performance metric, and signals applied to compensation of the drifting atmosphere are generated for tip-tilt mirror. The sensitivity of the performance metrics is investigated, and the convergence rate and the stability are analyzed. By means of this optimization algorithm, the centroid of the image is modified in real time, which results in the improvement of the long exposure image.
Thermal difference analysis and athermalization design of infrared optical system
Xing-qiao Ai, Bo Liu, Xin Zhang, et al.
When infrared optical system works in a large temperature range, the thermal effect of optical lens and optical tube will produce image plane shift and lead to imaging quality deterioration. In order to eliminate the thermal aberration, the athermalization design principles of infrared optical system were introduced, and some commonly used methods of thermal difference compensation were described. Proceeding from single lens, the thermal difference caused by temperature changing was analyzed, and the relationship between temperature and focus shift was obtained. Considering optical tube thermal expansion, a set of equations to estimate the thermal difference of lens group was given. Finally, an infrared optical imaging system that can work under the temperature range of -40°C to 60°C was design according to athermal technique, in which a new mechanical passive temperature compensation was proposed. Through simulation, the athermalization design could make imaging plane shift the smallest. The simulation results coincided with the theoretical formula, and the design had reference value in engineering.
Comparison of two stitching algorithms for annular subaperture Hartmann Shack testing method
Hongyan Xu, Hao Xian, Yudong Zhang
Annular subaperture stitching method is an effective method for testing aspheric surface. Two stitching algorithms for annular subaperture stitching method based on Hartmann Shack sensor are presented. The precision of the stitching algorithms is a major concern. The precision of the two algorithms are analyzed and compared in pertinent cases especially for the tested aspheric surface with different asphericity. The analysis shows that the phase stitching algorithm (PSA) can be used to reconstruct the whole-aperture wavefront for mild aspheric surface and the gradient stitching algorithm (GSA) can reconstruct the whole-aperture wavefront with high precision even for the steep aspheric surface with high noise level of gradient data.
Design of IR correctors for ground aspheric surface
Yongqian Wu, Yudong Zhang
The optical design and analysis of a two-element IR Offner-type null corrector for ground aspheric surface is presented. The optical system assumes an interferometer that consists of a point source, a 110 mm diameter relay lens, and a 10 mm diameter field lens. The aberration of the IR null correctors is PV0.0009λ.
Test for optical systems in laser projection imaging for PCB
Ouyang Qin, Jinyun Zhou, Liang Lei, et al.
Projection imaging is one of the most important steps in the fabrication of Printed Circuit Board. In order to meet the increasing demand for higher resolution, speed and larger area of imaging, a novel Laser Projection Imaging (LPI) has been developed to take the place of the conventional Hg lamp exposure. We set up a system with resolution 10μm over large exposure area of 460mm×610mm on substrate materials. The system is available by the combination of three main parts: an XeF excimer laser with a wavelength of 351nm and single pulse energy of 120mJ, an illumination system with numerical aperture (NA) value of 0.02, and a double telecentric optical projection lens with NA value of 0.025. Such designs can theoretically meet the demand of actual lithography. However, experiments have shown that the propagation loss ratio of laser power from the light source to the substrate can be up to 50% or more so as to hardly achieve the expected results. In this paper, we present our results of experiments under different conditions on laser projection imaging equipment, and meanwhile, parameters such as gas lifetime, pulse repetition rate, exposure dose, as well as the optical lose of quartz microlens array are analyzed. Finally, we acquired the optimum exposure parameters.
Design of a testing compensator for F/3 hyperbolic mirror
Yinghua Yuan, Jianjun Hu, Junhua Pan
The design principles of three familiar compensators are introduced. They are null lens compensator, offner compensator and reflective mirror compensator. Base on the three different theories, three different kinds of compensators for the testing of F/3 hyperbolic mirror are designed. The initial parameters of every compensator are analyzed in detail. The residual wavefront error, RMS radius of the spot diagrams and the tolerance of the three compensators are presented respectively. Due to the residual wavefront error consisted in these compensators themselves, higher order aspheric terms will be introduced into the hyperbolic mirror when using these compensators to test the mirror during the process of the fabrication. These higher order aspheric terms will influence the image quality of R-C system which primary mirror is this hyperbolic mirror. The simulation of this influence is analyzed in this paper. The residual wavefront error of the three final designs are all less than λ/30. The RMS radii of the spot diagrams are all less than 0.48μm.
The invariant statistical rule of aerosol scattering pulse signal modulated by random noise
Zhen-gang Yan, Bao-Min Bian, Juan Yang, et al.
A model of the random background noise acting on particle signals is established to study the impact of the background noise of the photoelectric sensor in the laser airborne particle counter on the statistical character of the aerosol scattering pulse signals. The results show that the noises broaden the statistical distribution of the particle's measurement. Further numerical research shows that the output of the signal amplitude still has the same distribution when the airborne particle with the lognormal distribution was modulated by random noise which has lognormal distribution. Namely it follows the statistics law of invariance. Based on this model, the background noise of photoelectric sensor and the counting distributions of random signal for aerosol's scattering pulse are obtained and analyzed by using a high-speed data acquisition card PCI-9812. It is found that the experiment results and simulation results are well consistent.
The analysis of the wavefront aberration caused by the gravity of the tunable-focus liquid-filled membrane lens
Wei Zhang, Pengfei Liu, Xiaona Wei, et al.
Liquid lens is a novel optical device which can implement active zooming. With liquid lens, zoom camera can be designed with more miniature size and simpler structure than before. It is thought that the micro zoom system with liquid lens has a very wide potential applications in many fields, in which the volume and weight of the system are critically limited, such as endoscope, mobile, PDA and so on. There are mainly three types of tunable-focus liquid lens: liquid crystal lens, electrowetting effect based liquid lens and liquid-filled membrane lens. Comparing with the other two kinds of liquid lens, the liquid-filled membrane lens has the advantages of simple structure, flexible aperture and high zooming efficiency. But its membrane surface will have an initial shape deformation caused by the gravity when the aperture of the lens is at large size, which will lead to the wave front aberration and the imaging quality impairing. In this paper, the initial deformation of the lens caused by the gravity was simulated based on the theory of Elastic Mechanics, which was calculated by the Finite Element Analysis method. The relationship between the diameter of the lens and the wave front aberration caused by the gravity was studied. And the Optical path difference produced by different liquid density was also analyzed.
Using different interpolation techniques in unwrapping the distorted images from panoramic annular lens camera
Guo Yu, Lingjin Fu, Jian Bai
The camera using panoramic annular lens (PAL) can capture the surrounding scene in a view of 360° without any scanning component. Due to severe distortions, the image formed by PAL must be unwrapped into a perspective-view image in order to get consistency with the human's visual custom. However the unfilled pixels would probably exist after unwrapping as a result of the non-uniform resolution in the PAL image, hence the interpolation should be employed in the phase of the forward projection unwrapping. We also evaluated the performance of several interpolation techniques for unwrapping the PAL image on a series of frequency-patterned images as a simulation by using three image quality indexes: MSE, SSIM and S-CIELAB. The experiment result revealed that those interpolation methods had better capability for the low frequent PAL images. The Bicubic, Ferguson and Newton interpolations performed relatively better at higher frequencies, while Bilinear and Bezier could achieve better result at lower frequency. Besides, the Nearest method had poorest performance in general and the Ferguson interpolation was excellent in both high and low frequencies.
Design of the structure parameters of photo-resist grating
Xinrong Chen, Chaoming Li, Jianhong Wu, et al.
The pulse compressed grating (i.e. PCG) is the key optical element in high power laser system. In order to obtain the PCG with high diffraction efficiency, it is necessary to design the required structure parameters of the photo-resist grating which is used as the mask of fabricating the PCG in process of etching. The rigorous couple wave theory is adopted to study and search for the suitable structure parameters of the PCG with the 1740lp/mm space frequency and particular basement of dielectric stack films which could produce more than 97% diffraction efficiency. Then the required structure parameters of the mask which is corresponding to those suitable structure parameters of the PCG are determined under some etching technological conditions. In studying the relationship between the diffraction efficiency of the mask and its structure parameters, we found that we could estimate the structure parameters of the mask by its -1st order diffraction efficiency. Then a simple and practical method which can estimate the structure parameters of the photo-resist grating according to its diffraction efficiency is proposed. The measuring setup based on this method is built and the veracity of this method is verified by experiment. The experiment result is present in the paper.
A multispectrum fish-eye lens for rice canopy detecting
Zhi Huang, Jian Bai, Xiyun Hou
In this paper, a fish-eye lens used for detecting rice canopy has been presented. This is a small lens with broad spectrum detection. The lens is composed of two groups, with three changeable optical filters between them. The filters can be changed automatically by stepper motor. All the data can be analyzed immediately by the laptop computer. The first sample lens shows its good performance of image quality and portability for outdoor operation.
A method of video analysis in vehicle based on a single PAL camera
Yi Yang, Guo Yu, Jian Bai
In this paper, we proposed a video analysis system in a vehicle using Panoramic Angular Lens (PAL) camera. The system consists two parts: one is using a PAL camera which is installed on the top of the vehicle to obtain obstacle position and compute the distance from the vehicle; the other is to configure a PAL camera inside the vehicle, which can provide the driver's face pose and eye status information as well as the driver's viewing scene, then several image algorithm are applied to analyze the status of driver and detect the object in front of the vehicle. Our contribution is that the large field view of PAL camera is well used in the application of Intelligent Transportation System, and to research the vehicle and driver information at the same time with a single panoramic camera. Meanwhile the system was very simple.
Gimbal displacement error analysis on an electro-optical seeker
It is essential to analyze the gimbal displacement errors for a seeker due to the importance for cueing of targets and tracking for the final approach. Otherwise, for a seeker electro-driven with a concentric glass dome, the large errors will decrease the picking, pointing, and tracking precision rooted from the displacement errors existing between the rotation center of the optical system and the gimbal. And the gimbaled camera system displacement errors are never eliminated but reduced due to the geometric errors consists of geometric tolerances of gimbal structure, manufacture, installation and vibration coming from working environment. In this paper, the gimbal displacement errors in an electro-optically stabilized platform resulting from geometric errors and environment errors were analyzed and shown in detail. The mathematical modal of the gimbal displacement errors created based on multi-body dynamics demonstrated the connection between the gimbal displacement errors and the stabilized platform. Taking a visible light image seeker as a case, the diameter is 120mm, and the geometric tolerances came from the values of primary design and the vibration data came from the environmental vibration test on the pitch-yaw seeker, and at the same time, the errors resulting from installation were considered too. Based on calculating, the maximum gimbal displacement error will reach to 0.2mm for pitching angle smaller than 40° and yawing angle smaller than 60°. However, the critical parts have been found out according to the probability theory and the reliability analysis successfully used in the paper, and finally, the maximum gimbal displacement error reduced to 0.1mm, which is acceptable corresponding to the picking, pointing and tracking precision for an optical imaging seeker.
Design of a laser transmittance measurement system
Qianqian Wang, Minglei Li, Zhe Liu, et al.
A laser transmittance measurement system designed to measure the transmittance of lasers passing through propellant plumes with wavelength 0.808μm, 1.06μm and 10.6μm is introduced in this paper. The transmission method is applied as the measurement method and the lasers are modulated with certain frequencies. By measuring the laser impinging intensity and the laser emerging intensity of the plume, the transmittance of the plume can be calculated. A microprocessor is applied for system controlling and data processing. Meanwhile, the measurement results are transmitted to a computer through the serial port, corrected automatically and shown in real time. As a result the data can be saved and printed for future analysis. Based on the results of system performance trial, this system fulfills the accuracy, stability requirements as designed.
Development of a real time MTF test bench for visible optical systems
Xinhua Chen, Yuheng Chen, Jiming Fan, et al.
A real-time MTF test bench for visible optical systems is presented in this paper. This test bench can perform quick on-axis and off-axis MTF measurement of optical systems whose aperture are less than 200mm in visible wavelength. A high quality off-axis parabolic collimator is used as object generator of this test bench. The image analyzer is a microscopy with CCD camera installed on a multi-axis motion stage. The software of this MTF test bench provides a good interface for the operators to set measurement parameters and control this bench. Validation of this test bench, performed with a 50mm plano-convex audit lens, shows that MTF measurement error of this bench is within 0.04. Besides MTF measurement, this bench can also perform effective focal length (EFL) and back focal length (BFL) without any hardware modification. Transmittance of optical system can also be performed on this bench with an integrating sphere.
Numerical study of fluid properties in opening-up optical fibers
Yi Yang, Jian Cui
The Finite Element Method (FEM) analysis about fluid properties in opening-up optical fibers which are designed for fluid sensor is presented. A FEM fluid-optical interacting model is founded by combining the Navier-Stokes equations and Maxwell equations. The analysis focuses on the relationships between fundamental sensing ability and fluid characters in the wagon wheel opening optical fiber which has one opening cladding holes. The Monte Carlo Method (MCM) is adopted for sensing error evaluation. 2D and 3D models are found for time-vary sensing analysis. The time-vary simulations show that the sensing result for dynamic fluid deviate from its static state. Some propose about opening-up optical fiber sensing design are presented too.
Testbed for an adaptive secondary mirror of 1.8m telescope
Xinlong Fan, Chunlin Guan, Changhui Rao
Testbed for an adaptive secondary mirror of 1.8m telescope is a system, which originates from Simpson-Oland-Meckel method. The testbed is composed of Hartmann-Shack (H-S) wavefront sensor, Hindle element and analysis element. Light from H-S wavefront sensor passes through the Hindle element and reflects off of the adaptive secondary mirror. It then is reflected by the concave surface of the Hindle element. After reflecting off of the adaptive secondary mirror again, it passes through the Hindle element and return to the H-S wavefront sensor. A beam splitter is placed between H-S wavefront sensor and Hindle element to reflect part of the output light to analysis element. The testbed is a low cost simple system that allows testing the convex hyperboloid adaptive secondary mirror. It also could be used to calibrate the adaptive secondary mirror as well as investigating higher performance control loops. Optical setup design, tolerance of fabrication, alignment and material asymmetry are presented in this paper.
Analysis of heat dissipation for integrated high-power LED lamp
Lanfang Jiang, Hong Liu
LED light source is considered as one of the important way for power saving and environmental protection. In this paper, a heat dissipation method for integrated high power LED lamp was investigated to solve its heat dissipation problem in engineering application. Firstly, the heat generation characteristics of integrated high power LED light source and the demand of heat dissipation of LED lamp were analyzed, and a heat dissipation analytic model was set up. Secondly, optimization of fins of radiator was carried out and optimal result was obtained. Thirdly, the result was applied to guide the radiator design of integrated high power LED street lamp. Lastly, the numerical simulation and temperature experiment of radiator were performed. Experiments shown that the radiator design satisfies the demand. It is of importance to guide the radiator design for LED Lamp.
Research and analysis of edge backlighting light guide panel for handset
Jun Zhang, Wen Gu, Zhe Chen, et al.
LCD and edge backlight light guide panel (LGP) are one of the main parts of handset or mobile phone et al. The design of LGP is vital technique to the design of backlight module. The aim of this paper is to design a handset LGP with LED as the light source. Three design qualifications are simulated and analyzed with ASAP software. The three qualifications are rough surface, diffusion-dots and microstructure. The analysis result shows that the factor of diffusion-dots is the most important ingredient. The surface brightness, the luminance distribution and the light efficiency of LGP are determined by the density of diffusion dots. The total light loss is also affected by the factor of diffusion-dots to the LGP whose diffusion dots are printed. A handset LGP is designed according to the research in the paper. The simulation result is satisfying as good as the practical outcome. The paper is useful to increase the brightness and uniformity of handset LCD.
The concept of constructing system for adaptive-selective assembly of optical devices
O. A. Vinogradova, A. D. Pavliy, A. D. Frolov, et al.
The factors influencing the possibility of partial automation of the assembly process and quality control of lens microscopes. Proposed engineering solutions, and booth setup.
The wavefront sensorless adaptive optics correction for a wide field of view optics system based on the SPGD algorithm
Xiaofang Zhang, Jing Guo, Xiaofeng Ren, et al.
The space adaptive optics system used for space remote sensing system to improve the image quality will face the challenge from the wider field of view. In this paper, the SPGD algorithm is present to realize the wavefront sensorless adaptive optics correction for a wide field of view optics system. Giving the traditional TMA optics system as the example, the image quality of different field of view is analyzed when there are some different surface errors in the optics system. The gradient evaluation method and convergence of SPGD is analyzed in detail. The issue of parameter such as the gain and step selection for SPGD is discussed. Computer simulation of a remote sensing AO system based on SPGD is studied. And the results show that wavefront sensorless wide field of view adaptive optics correction based SPGD algorithm for the segmented primary mirror system is acceptable, and the wavefront error is within 1/10λrms.
Design of imaging spectrometer based on Czerny-Turner in FUV
It is the astigmatism that leads the traditional imaging spectrometer based on Czerny-Turner to have low spatial resolution. And it is discovered that when the distance between concave mirror and grating, x, is equal to the twice of focal length, ƒ, of the mirror, SII = SIII = 0 and the aberration is the least as well as the astigmatism is eliminated greatly. Meanwhile the toroidal mirror is presented to correct the astigmatism, and as well the aberration caused by the large FOV is corrected by optimizing the surface tilt. Then both of the spatial and spectral resolutions are improved. Finally a Czerny-Turner imaging spectrometer working in FUV (120 nm ~ 180 nm) with 2.5° FOV is designed, and its focal length is 147.61 mm, its F number is 3.93. MTF of this imaging spectrometer is more than 0.39 at 20 lp/mm in the total wavelength band of FOV, which satisfied the requirements of imaging spectrometer working on satellite in FUV.
The optical system design and application of micro 2D barcode
Yi-jia Zhu, Liang-liang Li, Cheng Qian, et al.
We show an optical system of micro visual tag which is based on the principle of microscope and the property of QR Code. Unlike current optical tag, such as barcodes, must be read within a short rang and occupy valuable physical space on products, the new tags can be shrunk to several millimeters and captured from a distance of over 0.5 meters. We design the transmitter according to the parameters of camera lens. We also take the detection range and apertures into account, meanwhile conduct simulations and experiments. The result shows that: the tag can be captured from a long distance, and the amplified image is able to accurately be decoded.
Novel algorithm for compensating misalignment in optical spherical surface testing
Jinchun Zhang, Kaiwei Wang, Jian Bai
A novel algorithm for compensating misalignment in optical spherical surface testing is presented in this paper. In this algorithm a best fit sphere is found to compensate misalignment. It is found by minimizing the deviations among the tested surface and itself. Both the numerical and real data experiments have proved the validity of this algorithm. A spherical surface is tested and successfully compensated misalignment at different level.
Lunar-based solar telescope of multi-wavelength
Since the absorption of ultraviolet radiation in the atmosphere is strong, it is difficult to image solar UV radiation using ground-based telescopes. While, the moon which has no atmosphere and has stability geological structure and low magnetic field, observing the sun on the moon is more suitable than observing the sun on the earth. This paper describes the design of lunar-based solar telescope which can image the sun in three wavelength: long-wave IR (8-12μm), visible (400-900nm) and UV(100-400nm). The telescope is mainly composed of two parts: reflective telescope and splitting system. This design effectively avoids the material restrictions of IR and UV imaging optical systems. The rationality of the optical system design of the common aperture multi-wavelength telescope was proved by comparing the results with the images get by single wavelength solar telescopes all over the world. Compared the images took under different weather, the importance of the proposition of lunar-based devise is proved. Combined the splitters and the spectral response range of detectors, the UV, visible and IR can be split and imaged by different detectors.
Optical lens design with forced performance for metallographic light microscope
We present results of optical lenses with special design features for the assembly forced metallographic light microscope. Presented lenses satisfy the requirements of the linear field, the correction of aberrations.
Directional design of optical lens based on metallic nano-slits by Yang-Gu algorithm
Directional design of optical lenses based on metallic nano-slits that can focus light in different style by Yang-Gu (YG) algorithm. Both of the relative phase and amplitude of emitting light scattered by surface plasmon in a single subwavelength slit and modulated by the width of the slit or the thickness of the lens of the lens have been considered in the design processing. A form of the YG algorithm which considers both the phase and amplitude changing is derived. Two kinds of nanolenses are designed by this numerical method, one with one focal spot, and another with two focal spots in one focal plane. According to the finite-different time-domain (FDTD) method numerical calculation, it is found that the functions of the designed lenses agree well with preassigned goal. This method may be useful to design subwavelength optical devices that can be integrated into other optical and optoelectronic elements.
A sub-aperture scanning method for detecting wavefront of long-focus lens
Yao Li, Jing Wang, Changlun Hou, et al.
To detect the wavefront of a long-focus lens, a new method is proposed in this paper. It is based on two dimensional sub-aperture scanning and model method reconstruction. The number of stripes moved from one sub-aperture to another has a relationship with the wavefront slope. In most cases it can be approached to linear relation. Through scanning the initial wavefront slope data are achieved. Then with the slope data, the wavefront is reconstructed by model method with Zernike polynomials. Singular value decomposition method is used in the process of solving the matrix equation. Stripe-counting is one of the most important contents, which plays a decisive role in getting an accurate experimental result. The method's precision is validated after comparing it with laser interferometer. It also works in some situations that interferometer will not be suitable to detect a long-focus and large-diameter lens.
Optical design used in Z-stack imaging based on liquid lens
Tianling Yang, Liqiang Wang, Huilong Duan
Z-stack imaging system drives microscope to scan one image plane, changes the depth of the focus, and then scans another plane, last gets the data of examination sample. The curvature of liquid lens can be changed according to changes in the characteristics of voltage. It leads to achieve miniaturization and simply structure of focus imaging system. This article uses CODE V to design a microscope objective which employs an Arctic 416 liquid lens. It proposes architecture of 5 groups of lens with 40× microscope objective lens, 0.65 numeral aperture and 0.52° field of view (FOV). By CODE V automatic design, the microscope objective lens achieves a continuous focus adjusting up to 120μm depth. And then a better FOV MTF value with the same continuous focus range can be obtained by reducing one of lens group. Lastly, by replacing the high performance material of glass, the FOV achieves higher MTF and the continuous focus range increases to 130μm.
Measurement of the radius of curvature of a mini spherical surface with virtual grating phase shift technique
Spherically optical components of small diameters have found wide applications in many fields. Radius of curvature (ROC) is an important parameter as it determines their optical characteristics. For measuring the ROC of a mini spherical surface, a static microscopic carrier interferogram is taken, and virtual grating phase shift technique (VGPT) is adopted in this paper. By using the computer, four virtual gratings are generated, their reference frequency being the same as the carrier frequency of the test interferogram, and their modulation phases being 0, π/2, π and 3π/2, respectively. By multiplying the test interferogram separately with the four virtual gratings in intensity, four moiré fringe images are obtained. By applying Furrier transform and low pass filtering, a set of four carrier-free phase shift fringe images are obtained. And finally by applying four step phase shifting algorithm and least square fitting (LSF), the ROC of the test spherical surface is obtained. Furthermore, the result agrees well with its nominal value and measurement result by Zygo interferometer. This indicates that adopting VGPT for measuring ROCs of mini spherical surfaces is practicable and has relatively a high accuracy.
Optical system design of surface roughness photoelectric inspection instrument
Ze-xin Xiao, Peng Li, Jie Cao, et al.
The light-section method for roughness measurement is one of the most classical measuring methods. According to light-section method which combine visual observation with photomicrography for testing surface roughness, domestic type of 9J is a traditional device. The surface roughness photoelectric inspection instrument which designed by the authors are also based on the theory of light-section, which integrates subjects of optics, mechanical, electronics and calculation. Surface roughness of object image can be obtained on the CCD sensor through the optical system. Using the autonomous software in the computer, the average height of workpiece unevenness Ra value can be measured and read in the monitor. Therefor, surface roughness level can be obtained. In order to design the optical system of device, there are three main aspects which should be finished: 1.Start with requirements of detective object, according to the detective range from Ra12.5 to Ra0.04 ruled by CNS(China National Standards) GB3505-83 the Surface Roughness Term Surface and the Parameters ,parameters on β(magnify power), NA(numerical aperture), WD(work distance), filed of object etc are defined and optimized. Meanwhile, good complementation and compatibility are noticed among three kinds magnification objectives. 2. Special type infinity image distance double telecentricity optical system is constructed. The main point is to design a set of objectives of long WD and infinity image distance flat field semi-apochromat. 3. How to match and optimize the CCD image sensor and lens.
Research on the surface reflectance measurement of optical element with transparent substrate
Guo Xia, Xingzhi Gong, Liang Cheng, et al.
Because of the substrate back reflectance phenomena, the reflectance of optical elements on a transparent substrate is totally different from that of on an opaque substrate. In this paper, the differences between normal and quasi-normal substrate back reflectance are analyzed for the first time. Then a detailed study of the influences of the substrate thickness, substrate material, measuring distance and other parameters in the measurement are performed, the computational expressions of fitting surface reflectance are derived, and a compensation model of the substrate back reflectance measurement is proposed. Simulation and experimental results prove the correctness of the theoretical model and show this compensation model can be used in the substrate back reflectance measurement.
System tolerance analysis of dual-advantage spectrographic system based on coded aperture
Traditional dispersive spectrographic systems based on single slits cannot achieve dual advantages simultaneously and statically. A novel dual advantages system model for dispersive spectrographic system appears and the traditional entrance slit is replaced by a coded aperture based on orthogonal independent column codes. The extended aperture lets more energy enter the system and the independence of the codes helps to avoid degradation of the spectral resolution. On the basis of the derivation of system model, this paper emphasizes on system tolerance analysis, to find out the key factors which affect the realization and performance of the system model. First, the influences of inaccurate system adjustment and calibrations on system performance were studied. The standard methods for system adjustment and calibrations were represented. Then, simulations were carried out to study the influence of several abnormal situations of the coded aperture on system performance, which includes the existing of error fabrication and imperfect illumination of the coded aperture. The analysis result shows that the system can still function normally when the coded aperture has a fabrication error rate of 30% or severe imperfect illumination of the coded aperture.
Three-channel off-axis three-mirror system design and analysis
Xiaoping Li, Zhonghua Fang, Xinglong Li
This paper analyzed the structural and imaging features of off-axis three-mirror system, discussed the design method of the multi-channel off-axis three-mirror system. A new three-channel off-axis TMA optical system was designed using channel spectral separation. The system parameters are as follows: aperture is 300mm, FOV is 2°×2°, covering three spectral bands. According to the primary aberration theory, an appropriate initial configuration can be obtained. By optimizing the initial configuration, we can get an optical system which meets the imaging quality requirement. The design of relay lenses was also considered, the ultimate goal is to complete the design of each channel with the least number of lens.
Large area two-dimensional scanning model and image rotation analysis
Xiaoping Li, Xinglong Li, Zhonghua Fang
Nowadays the remote sensing instruments require relatively larger FOV and higher LOS pointing accuracy. However, the traditional scanning model can only have a relatively small scanning area. As the scanning area increases, the image rotation will increase rapidly. The traditional two-dimensional scanning model has failed to meet the growing demands of remote sensing instruments. To solve the problem, in this paper, the differences of all kinds of two-dimensional scanning method are analyzed and compared, and different ways to place and rotate two-dimensional scanning mirror are also considered. Finally, through analysis, a kind of two-dimensional scanning model which meets the large area two-dimensional scanning requirements was obtained. At the same time, the image rotation of large area two-dimensional scanning model is analyzed, which provides data support for image processing.
Design of a four-mirror optical system with wide field of view
Shi-tong Liang, Jian-feng Yang, Bin Xue, et al.
Reflective optics is used widely in space optical systems for their achromatization, large aperture and lightweight compared with refractive systems. Four-mirror system especially off-axis system is desired for its excellent imaging performance and compact structure. Aberration theory of coaxial four-mirror system based on PW method is analyzed and the design procedure is proposed to get the initial four-mirror system in this paper. A large field off-axis four-mirror system is designed based on the theory and the design process. The system contains four conic aspheric mirrors. It has a 2°×0.32° rectangular field of view. The MTF of the system is diffraction-limited and the distortion is less than 0.1%. The structure of the system is compact and the ratio of total axis length to focal length is about 1/3.9. The excellent imaging performance and compact structure make it adaptable to space remote sensing systems.
Research on measuring optical transfer function
Shaojun Lu, Xiaolin Zhang, Rongli Guo, et al.
Optical transfer function (OTF) of optical system is an important character to show optical system's imaging quality. It is important to accurately obtain the OTF in optical measurement. But traditional methods encountered some difficulties in high-precision measurement. A new approach based on digital image processing technique (DIP) is proposed in this paper. An experiment is done to acquire the image of a pill and a CCD is used to acquire digital images. Optical-electronic focal plane fixing technology is adopted to obtain a more accurate image. Then the images are done by digital image processing, including filtering and Fast Fourier Transform, and the 2-dimension modulated transfer function (MTF) is obtained. The MTF of this detected lens derived from this way is compared with a higher accurate equipment to measure the OTF of the same lens, the results have some differences. The reason is analyzed in this paper. This method will be widely used in optical inspection.
Study on testing resolution of optical system
Shaojun Lu, Xiaolin Zhang, Rongli Guo, et al.
Resolution of optical system is a critical index to judge the quality of optical system. Measuring the resolution of optical system has become more and more important in optical measurement. But traditionally the method to evaluate the resolution of optical system is mainly subjective because of man's eye seeing. Although this method is simple and intuitive, it is very easy for the introduction of the subjective error. To solve this problem, an approach based on digital image processing technique is brought out to achieve this subjective processing in this paper. An experiment is done to grasp image of resolving power test target formed by a teleobjective, its extreme resolution is obtained. The result matches ideal resolution by calculation. This way has the advantage of rapid processing and objective. It is the tendency of measuring resolution in the future.
The optical design and simulation of multi-chip LED array package structure
Hong Wang, Li Chen, Feifei Ye, et al.
Based on the non-imaging particularities of LED optical sources , considering the impact of several factors respectively such as the distribution of chips, the size of the reflector and the refractive index of packaging material , the packaging of multi-chip LED array source is designed and simulated by using geometrical modeling for optical components and Monte Carlo non-sequence ray tracing method. In this paper put emphasis on the optical design of the packaging structure to the 2 × 2 LED array source, and get the different luminous efficiency and light intensity distributions by changing the packaging parameters of the model. The results showed that the distributions of light intensity under the different parameters have certain regularity. These laws have the practical guidance to the multi-chip LED lighting system design and production, and these are also helpful to reduce the experiment costs in LED packaging manufactures.
Design and fabrication of a two-beam prism interferometer
M. Abolhassani, M. Esmaeili
A new type of amplitude-division two-beam interferometer using a prism is proposed. The prism performs the beamsplitter and one arm of the interferometer. Any plane parallel plate is not employed in the interferometer, and any of its components surfaces doesn't need to anti-reflecting or semi-transparent coating. It doesn't produce spurious fringes when is well-adjusted. In the case of using a monochromatic point source, quality of the fringes obtained by this interferometer is comparable with the one obtained by the Michelson interferometer.
Optical design of high resolution and large format CCD airborne remote sensing camera on unmanned aerial vehicle
Yixian Qian, Xiaowei Cheng, Jie Shao
Unmanned aerial vehicle remote sensing (UAVRS) is lower in cost, flexible on task arrangement and automatic and intelligent in application, it has been used widely for mapping, surveillance, reconnaissance and city planning. Airborne remote sensing missions require sensors with both high resolution and large fields of view, large format CCD digital airborne imaging systems are now a reality. A refractive system was designed to meet the requirements with the help of code V software, It has a focal length of 150mm, F number of 5.6, waveband of 0.45~0.7um, and field of view reaches 20°. It is shown that the value of modulation transfer function is higher than 0.5 at 55lp/mm, distortion is less than 0.1%, image quality reaches the diffraction limit. The system with large format CCD and wide field can satisfy the demand of the wide ground overlay area and high resolution. The optical system with simpler structure, smaller size and lighter weight, can be used in airborne remote sensing.
Research on calibration of three-mirror reflective space remote sensor using wavefront sensorless method
Position errors of three-mirror reflective space optical system will affect the whole system badly, so we have to calibrate these errors in orbit. This paper proposes a new method for the first time, which is: we can use Stochastic Parallel Gradient Descent algorithm to calibrate three-mirror reflective remote sensor, this method don't need wavefront sensor to calibrate position errors. It uses root mean square of radius of image as system merit, through controlling the six position of second mirror to compensate system error. This method is suitable for the calibration of three mirror reflective space optical system for its needless of using wavefront sensor. Results of the simulation show that compared with traditional sensitive matrix inversion algorithm, this method increases the dynamic range of initial position errors, and it can improve wavefront error from about 1 wave rms to lower than 0.04 wave rms in the center field of view.